add new helper function

utils/http.go

@@ -0,0 +1,12 @@
+package utils
+
+import (
+	"encoding/json"
+	"net/http"
+)
+
+func SendJSONError(w http.ResponseWriter, message string, code int) {
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(code)
+	json.NewEncoder(w).Encode(map[string]string{"error": message})
+}